It is proposed that decreased left ventricular function results in baseline alterations in the pulmonary system secondary to chronic pulmonary congestion and poor perfusion to the respiratory muscles. Exercise causes further pulmonary congestion and combined with the poor respiratory muscle function alters breathing pattern, pulmonary mechanics, gas exchange, and subsequently, performance. In addition, it is proposed that negative intrathoracic pressures increase cardiac afterload further compromising cardiac output. These hypotheses will be tested by accomplishing the following specific aims. 1. To determine the degree to which patients with CHF approach the limits of their lung and respiratory muscles for producing airflow, volume, and pleural pressure during exercise. 2. To determine the degree to which patients with CHF develop pulmonary congestion during exercise. 3. To determine the influence of intra-thoracic pressure changes on exercise tolerance and cardiac output in patients with CHF. 4. To determine if inhalation of a specific alpha-adrenergic agonist methoxamine reduces the degree of exercise induced pulmonary congestion and improves lung mechanics and exercise performance in patients with CHF.